This invention relates to video communication systems for televising remotely located conference rooms and, more particularly, to improvements in voice-operated switching circuits for selective and automatic actuation of the system.
Audio or voice-operated switching circuits are known in the art and have a primary area of application, for example, in two-way video communications systems for connecting two or more groups of remotely located conferees to simulate a face-to-face meeting. The video systems are usually comprised of a plurality of cameras at each remote location (e.g., a conference room) directed toward the various conferee-speaking locations within the conference room. At each remote location one or more monitors, which are connectible to a plurality of cameras at the other remote locations, are available for viewing by each of the conferees or groups of conferees. In such applications, the voice-operated switching circuit is utilized to selectively and automatically activate the particular camera directed toward the location of the particular conferee speaking at any particular time while maintaining unactivated the plurality of other cameras in each conference room and, thus, cause the video image of the particular speaker along with the audio signal to be transmitted to the various remote locations and there be reproducible on the respective monitor and audio speaker systems at each location. Such circuits usually function (1) to control the video switching selection when conferees at the same location speak simultaneously; (2) to maintain the camera system in operation without interruption even though the conferee makes short pauses between words and sentences; and (3) to prevent actuation of the switching circuit by background noise of a low audible level or of a short duration. One such system is described in U.S. Pat. No. 3,601,530. The design of the switching circuits in this system has been found to be highly complex and expensive.
Accordingly, it is an object of this invention to provide an improved switching circuit for a conference room video communications system.
It is another object of this invention to provide an electronically simple voice-operated switching system which utilizes a minimum number of expensive integrated-circuit components.
These and other objects will be apparent from the following description taken in conjunction with the appended claims.